Precambrian Research ( IF 3.8 ) Pub Date : 2021-08-13 , DOI: 10.1016/j.precamres.2021.106344 Guangyou Zhu 1, 2 , Wei Liu 2 , Guanghui Wu 2, 3 , Bingshan Ma 1 , R. Damian Nance 4 , Zecheng Wang 2 , Yang Xiao 1 , Zhiyong Chen 2
The West Kunlun Orogenic Belt (WKOB) is a key area for evaluating the evolution of the Proto-Tethys Ocean. To constrain this history, we present geochemical and zircon U-Pb geochronological data from a suite of metasedimentary rocks within this orogenic belt. Detrital zircons ages are clustered between 1000 and 400 Ma, with major peaks at ca. 510 Ma and 460 Ma, and minor peaks at ca. 840 Ma and 650 Ma. The age groups younger than 1000 Ma broadly overlap magmatic activity at ca. 540–420 Ma and minor magmatism at 920–540 Ma in the WKOB. The age data also reveal Early Paleozoic metamorphic basement rocks in the WKOB that were probably sourced from Kunlun terranes and blocks of Gondwanan affinity rather than the Tarim Craton. Compiled geochemical data suggest a protracted subduction setting in the WKOB in the Early Paleozoic. εHf(t) values show increasing trends at 900–740 Ma and 740–600 Ma and a distinct decreasing trend at 540–420 Ma, consistent with retreating subduction during the Neoproterozoic and advancing subduction in the Early Paleozoic. The retreating-advancing subduction cycle in the WKOB was possibly related to the opening and closure of the Proto-Tethys Ocean along the margin of Gondwana.
中文翻译:
西昆仑造山带地体变质岩地球化学和U-Pb-Hf碎屑锆石年代学:原始特提斯洋最北端的长期俯冲
西昆仑造山带(WKOB)是评价原始特提斯洋演化的关键区域。为了限制这段历史,我们提供了来自该造山带内一系列变沉积岩的地球化学和锆石 U-Pb 年代学数据。碎屑锆石年龄聚集在 1000 到 400 Ma 之间,主要峰位于约 510 Ma 和 460 Ma,以及在大约 460 Ma 处的小峰。840 毫安和 650 毫安。年龄小于 1000 Ma 的年龄组在大约 WKOB 中的 540-420 Ma 和 920-540 Ma 的次要岩浆活动。年龄数据还揭示了 WKOB 中早古生代变质基底岩,它们可能来自昆仑地体和冈瓦纳亲缘岩块,而不是塔里木克拉通。汇编的地球化学数据表明早古生代 WKOB 中存在长期的俯冲环境。εHf(t) 值在 900-740 Ma 和 740-600 Ma 处呈上升趋势,在 540-420 Ma 处呈明显下降趋势,与新元古代期间俯冲后退和早古生代俯冲推进一致。WKOB 的后退-前进俯冲旋回可能与冈瓦纳大陆边缘原始特提斯洋的开闭有关。